Exposure apparatuses for semiconductor processing are commonly used to transfer images from a reticle onto a semiconductor wafer during semiconductor processing. A typical exposure apparatus includes an illumination source, a reticle stage assembly that positions a reticle, an optical assembly, a wafer stage assembly that positions a semiconductor wafer, a measurement system, and a control system.
The size of the images and features within the images transferred onto the wafer from the reticle are extremely small. As a result thereof, the precise positioning of the wafer and the reticle relative to the optical device is critical to the manufacture of high density, semiconductor wafers.